class Solution {
public:
    const int INT = 0x3f3f3f3f;
    int maxProfit(vector<int>& prices) {
        int n = prices.size();
        vector<vector<int>> f(n,vector<int>(3,-INT));
        auto g =f;
        g[0][0] = 0;
        f[0][0] = -prices[0];
        for(int i=1;i<n;i++)
        {
            for(int j=0;j<3;j++)
            {
                f[i][j] = max(f[i-1][j],g[i-1][j]-prices[i]);
                g[i][j] = g[i-1][j];
                if(j-1>=0)
                {
                    g[i][j] = max(g[i-1][j],f[i-1][j-1]+prices[i]);
                }
            }
        }
        int ret=0;

        for(int i=0;i<3;i++)
        {
            ret = max(g[n-1][i],ret);
        }
        return ret;

    }
};